Biocatalysts constitute an enormous and as yet untapped treasure trove for synthetic organic chemists. Although enzymes had been technically exploited long before their catalytic and chemical mechanisms were fully understood, their use as novel catalysts in organic fine syntheses has been the subject of substantial research only during the last 10 to 15 years. Since there exists an enzyme- catalyzed equivalent for most organic syntheses, one can expect that in the near future a steadily growing number of synthetic applications will emerge from this challenging area of enzyme technology. Our long range objective is to gain a better understanding of the stereoselectivity of biocatalysts, so that they may be used routinely as chiral catalysts for organic synthesis. Our immediate objectives are: to determine the kinetic parameters that govern enantioselectivity and to develop quantitative expressions that will allow the prediction of stereoselectivity; to develop strategies for enhancing optical purity of the chiral species during asymmetric catalysis and kinetic resolutions; and to show the usefulness of biocatalytic systems in the synthesis complex chiral molecules. Currently, we are focusing on the use of extracellular microbial lipases for catalyzing the formation of macrocyclic lactones in non-aqueous media. Synthetic targets include the antibiotics Pyrenophorin, Venturicidins, and Forskolin, a diterpene that displays bronchospasmolytic, anti-hypertensive and inotropic activities.